The present invention relates to plastic enclosures which can be stored and shipped as flat sheets but are capable of being folded up along flexible fold lines and locked together to make rigid boxlike enclosures, and, more particularly, to such enclosures which are suitable for use as wall-mounted electrical component enclosures, such as pull boxes, junction boxes, splice boxes, and equipment cabinets.
1. Description of Related Art
Electrical component enclosures, such as junction boxes, are commonly made from sheet metal. Because fabrication of sheet metal enclosures would be difficult and time-consuming if done on site by an end user, they are usually shipped preassembled, which means that shipping and storage space must be wasted on the empty volume within the enclosure.
During both the initial installation of electrical components within the enclosure and during subsequent repair of these components, an electrician's access to the electrical components is generally limited to a single open panel at the front face or at one wall of the enclosure. This restricted access often makes it awkward and difficult to work on the electrical components in the enclosure, which results in more time being expended on installation or repair than would otherwise be required if the sidewalls were not in the way.
Because it is relatively difficult to cut or drill holes into metal, an electrician is generally not completely free to run cable or conduit into a sheet metal enclosure at whichever location he desires, but, to the contrary, he is generally limited to standard size knockout holes which are provided at predetermined locations in the sidewalls of the enclosure. A further disadvantage of sheet metal enclosures is that larger enclosures can be difficult to mount on a wall because of their weight.
Known molded plastic electrical component enclosures and customized plastic enclosures which are solvent-cemented or glued together or heat-welded by hand are lighter, and can be cut or drilled more easily than metal enclosures, but they still have the remaining disadvantages of wasted shipping and storage space, limited access to components contained therein, and are relatively expensive.
Various methods of imparting fold lines to hard plastic materials are known. U.S. Pat. Nos. 3,292,513; 3,334,802; 3,350,492; 3,594,464; 3,768,950 4,373,929; 4,386,926; and 4,664,648; all disclose various techniques for cold-scoring plastic sheeting by means of mechanical deformation to create fold lines. Techniques for creating fold lines which involve a combination of heating to soften the plastic and mechanical deformation are disclosed in U.S. Pat. Nos. 3,379,814; 3,589,022; 3,907,193; 4,179,252; 4,642,086; and 4,946,430. U.S. Pat. Nos. 3,132,649 and 3,201,145 teach plastic molding techniques for imparting fold lines. These patents are generally directed to methods of providing fold lines in plastic sheeting used for packaging consumer goods, wherein the plastic sheeting is capable of being handled by high speed folding and filling machines. Foldable plastic containers produced by known techniques are generally not susceptible to reuse without substantial loss in utility, nor are they generally capable of being easily assembled without specially designed machinery and adhesive agents, nor do they have sufficient mechanical strength for construction-related applications.